Intrapopulation variation in macro tooth wear patterns--a case study from Igloolik, Canada.

The pattern of human tooth wear-the way it varies between teeth in the mouth-is crucial to our understanding of important questions in archeology and paleoanthropology, such as the contrasts in diet and behavior between Neanderthals and early modern humans in Europe and Asia, or with the adoption of agriculture in the Americas. Little is known, however, about the way in which wear patterns develop with increasing age or the way in which they differ between males and females. One explanation is that few living people show the high rates of tooth wear seen worldwide throughout the preindustrial archaeological record. The study described here investigates the macroscopic pattern of tooth wear in a unique group of known age and sex dental casts from living Canadian Inuit from Igloolik. The results show that the Igloolik people possessed a pattern of extremely heavy anterior tooth wear, relative to the first molar and the other posterior teeth, which is attributed to the use of the anterior teeth in cultural practices as well as the extreme and marginal environments in which they lived. Heavy anterior tooth wear was established at an early age and maintained throughout life; statistically significant differences were found between the wear patterns of males and females and are explained in terms of sexual division of labor within the community. This study highlights the need to understand both intra- and interpopulation variation in tooth wear patterns when interpreting patterns in past human groups.

Tooth wear, Neanderthal facial morphology and the anterior dental loading hypothesis.

The Anterior Dental Loading Hypothesis states that the unique Neanderthal facial and dental anatomy was an adaptive response to the regular application of heavy forces resulting from both the masticatory and cultural use of the anterior teeth. Heavy anterior tooth wear frequently observed in Neanderthal specimens is cited as a main source of evidence for heavy forces being applied to these teeth. From this, it might be predicted that the wear shown on the anterior teeth of Neanderthals would greatly exceed that of the posterior teeth and that this differential would be greater than in other hominins with different facial morphologies. In this paper, a new method of examining tooth wear patterns is used to test these predictions in a large assemblage of Late Pleistocene hominins and a group of recent hunter-gatherers from Igloolik, Canada. The results show that all Late Pleistocene hominins, including Neanderthals, had heavily worn anterior teeth relative to their posterior teeth but, contrary to expectations, this was more pronounced in the modern humans than in the Neanderthals. The Igloolik Inuit showed heavier anterior tooth wear relative to their posterior teeth than any Late Pleistocene hominins. There was, however, a characteristic Neanderthal pattern in which wear was more evenly spread between anterior teeth than in modern humans. Overall, the evidence presented here suggests that all Late Pleistocene hominins habitually applied heavy forces between their anterior teeth and that Neanderthals were not exceptional in this regard. These results therefore does not support the Anterior Dental Loading Hypothesis.

Brief communication: Additional cases of maxillary canine-first premolar transposition in several prehistoric skeletal assemblages from the Santa Barbara Channel Islands of California.

This article identifies and discusses seven new cases of complete maxillary canine-premolar transposition in ancient populations from the Santa Barbara Channel region of California. A high frequency of this tooth transposition has been previously documented within a single prehistoric cemetery on one of the Channel Islands. A total of 966 crania representing 30 local sites and about 7,000 years of human occupation were examined, revealing an abnormally high prevalence of this transposition trait among islanders during the Early period of southern California prehistory ( approximately 5500-600 B.C.). One of the affected crania is from a cemetery more than 7,000-years-old and constitutes the earliest case of tooth transposition in humans so far reported. The results are consistent with findings by other studies that have indicated inbreeding among the early Channel Islands groups. Together with the normal transposition rates among mainland populations, the decreasing prevalence of maxillary canine-first premolar transposition among island populations across the Holocene suggests that inbreeding on the northern Channel Islands had all but ceased by the end of the first millennium B.C., most likely as a result of increased cross-channel migration and interaction.